Nerve growth factor-induced loss of cell-associated nerve growth factor receptor in human melanoma A875 cells

Nerve growth factor stimulates in vitro invasive capacity of DU145 human prostatic cancer cells

The prevalence of nerve growth factor (NGF) production in different human prostatic tumor cell lines (DU145, PC-3, LNCaP-FGC) was investigated using a specific enzyme-linked immunosorbent assay (ELISA) and compared to that of different human and rat prostatic tissue samples. In addition, the biological effects of NGF beta addition to the human prostatic cancer cell cultures were investigated. The ELISA technique showed the DU145 cell line to secrete measurable levels of NGF in the culture medium. When neurite-outgrowth determination in a pheochromocytoma cell line was used as a bioassay, the NGF synthesized by DU145 cells was confirmed to exhibit functional biological activity. No effect of exogenously added NGF could be established on tumor cell proliferation, on the basis of either colorimetric tetrazolium-based staining assay or bromodeoxyuridine incorporation. Also the expression of prostate specific acid phosphatase was not influenced by NGF addition. However, the in vitro invasive capacity (Matrigel) of DU145 cells was significantly increased by inclusion of 50 ng or 100 ng NGF beta/ml culture medium. In view of the clinically well-known perineural invasion of prostate cancer cells, the possible involvement of NGF as a (paracrine) factor in prostatic cancer metastatic behavior should be investigated further.

Expression of nerve growth factor and epidermal growth factor receptors in neural nevi with nevic corpuscles

The histogenesis of "nevic corpuscles" (NCs) in neural nevi is still controversial. Recent studies have revealed that nerve growth factors (NGFs) and other growth factors [that is, epidermal growth factor (EGF)] could have various paracrine and autocrine functions on Schwann cells and melanocytes. We examined the immunohistochemical expression of NGF and EGF receptors (r) in 15 cases of neural nevi containing NCs along with 37 cases of other benign and malignant melanocytic lesions without neural differentiation (total, 52). Section were prepared from formalin-fixed and paraffin-embedded tissues. Monoclonal antibodies to NGFr and EGFr were used with the Avidin-biotin-complex (ABC) technique. We found strong reactivity for NGFr in 14 of 15 neural nevi with a predilection for NCs, but only eight of 37 were positive in the other group of melanocytic lesions without neural differentiation (four Spitz nevi, two melanomas, and two compound nevi). EGFr expression was limited mainly to NCs in four cases of neural nevi. We conclude that neural differentiation and NC formation are associated with NGFr overexpression, whereas EGFr expression is only limited. The relative paucity of NGFr expression in other type of benign and malignant melanocytic lesions supports the view that neural "differentiation" is a distinct process in certain long-standing melanocytic nevi. We postulate that NGFr overexpression may be the result of the reactivation of oncofetal genes that could become manifest in either abnormal schwannian differentiation (as seen in neural nevi), in a neoplastic context (as seen in neural and melanocytic tumors).